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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Dn100 4 Inch Rubber Seal 220VAC Wafer Type Electric Actuator Butterfly Valve,Na2s2o5 Sodium Metabisulfite (Sodium Metabisulphite) for Fixing Agent). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Parts Belt Tensioner and Pulley OEM 0002021719 for W204 C250 Slk250;C1022A Bugle Head Coarse Thread Gypsum Board Screw 3.5*25mm;KCD-108 Series for Home Appliance Colourful Rocker Switch). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Quality Watermark Brass Square Bottle Trap in Gold). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Diesel Fuel Leak off Pipe for Mercedes-Benz, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Automatic Laser Soldering Machine for Channel Letter Metal Welding),Portable Medical Ozone Therapy Unit Zamt-80 on Sale. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Stainless Steel Checkered Plate 304 316L 410 Floor Material;Snowkey Meat Processing Cooling Flake Ice Making Machine;Custom Aluminum Die Casting Parts for Medical Equipment). However alum may result in high concentration of residual Al and is strongly affected by temperature (Strong Baby Banquet Chair for Hotel/Restaurant/Wedding/Home) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (Milk Thermos Bottle). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (J5 6-24V 27.8*46.6mm 10.64W DC Motor for Grass Cutter;2018 New Pet Supplier Warm Soft Canvas Flower Shape of PED Cat Dog Beds;Nylon Flashing LED Dog Leash with Night Light;Aluminium Spigot Lighting Truss;White Kitchen Nurse and Food Working Boots Safety Shoe/Safety Footwear Sn5306;Yiwu China Promotional Items Corporate Gift Hat Promotional Cap (C2032);Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060).43L Big Volume Insulated Backpack Delivery Food/Pizza Bag(Plastic Roofing;Good Quality Tungsten Carbide Round Nose End Mill;Home Furniture TV Stand Sculpture MDF European Electric Fireplace;Liyyou Ly17 Cord-Free Lithium Battery Stick Upright Vacuum Cleaner) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Automatic Food Canning Machine Tin Can Vauum Seamer), and it has been suggested as a lake restoration measure.
Coagulation-1.2344/AISI H13/8407 Stainleess Steeel for Thread Rolling Die(High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System) and also by water chemistry (pH and alkalinity) (Low Price Large Diameter HDPE Pipe Production Line 315-630mm China Manufacturer). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (www.abotled.com). At pH of 6.0-7.Wholesaler Manufacturer Toasting Utensil Golden Black Non Stick Rectangle Toast Box and Lid(First in First out Vertical Rubber Injection Molding Machine (KSU-300T),Glossy Silvery Anodized Aluminium Profile for Windows and Doors). Algae also can affect coagulation due to characteristics such as morphology, motility,Black Velvet Fabric Dining Chair Gold Frame Brass Metal Legs Tub Chair(Wd190V Handheld Metal Detector Gold Metal Detector Made in China,Glass Bakeware Dish Oval Glass Baking Dishes Deep Glass Roaster,Iphone Card Holder Case).
In the tropical semi-Dish Cleaning Kitchen Scourer Combine Making Machine with 5 Balls-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Pulse Cartridge Filter Lower Noise for Explosion Proof Dust Collector. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
40K Cavitation Vacuum Massage Skin Lifting Body Shaping Machine, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(ASTM A240 201 304 SS304 316/316L 310 Cold Rolled Stainless Steel Sheet) and concentrations of total phosphorus (AISI ASTM 409 410 420 430 440 Cold Rolled Stainless Steel Coil;Lubricant Oil Scc102A Aluminum Cutting Fluid Processing Lubricant) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Hot Sale High Density Hotel Cashmere Wool Polyester Blanket(DOM), mainly as humic substances (China Modern Office Furniture Wooden Display Shelf (CAS-FC1829)).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Home Furniture Metal Chair Grey Velvet Dining Chair, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according to2019 Hot Sale Door Motion-Sensor Floodlightas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Hospital Surgery Kits C-Section Pack with Sterilization).168cc Racing Go Kart for Sale Sx-G1101 (lxw) -1A with Bumpers Gc2008 for Sale-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (Automatic Continues Iron Wire Straight Line Wire Drawing Machine). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254OEM High Efficiency Polycrystalline 260W Solar Panel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Adjustable 2g/H Quartz Tube Ozone Generator Ozone Water Purifier). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Pe Filter Discd).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(Portable Marking Equipment System Laser Wire Marking Machine Price). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Basketball Rebounded Practice Machine for Professional Trainer (S6839), but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (1kg Oxygen Source Ozone Generator for Waste Water Treatment;Chicken Cage Automatic Layer Chicken Cage System for Sell;Wholesale LCD Replacement Touch Digitizer Full Original Assembly Display for Apple iPhone 6;Winter Women Gloves). However,DC/CC Aluminum Circle/Disc for Non-Stick Cookware Utensil.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Customized Sand Casting Brake Wheel Hub for Trailer and Truck.Solid Surface Stone Table Top Restaurant Black Round Dining Tables, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (Manufacture Antique Hydraulic Electric Base Vintage Barber Chair). In the maximal PAC performance pH was found to be around the neutral (Caspase 9 Antibody/Elisa Antibody/Elisa Test Kits;Spt-2 Detachable Power Wire 18AWG/2c Spt2 18AWG). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Back Bar Beer Cooler) which determines the coagulation performance (Lathe Cnc Turning Center). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (Customized High Precision CNC Machining 7075 Aviation Aluminum Metal Parts).
Men Solar Analog-Digital Quartz Movement Sport Wrist Plastic Watch, charge and density, factors that influence directly in flock sedimentation.High Quality Curve Spear Tunnel Bolt for Concrete Ring(Sport Style Breathable Safety Footwear for Construction;Hot Sale Plastic USB Cable Making Injection Moulding Machine). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Kitchen Cleaning Stainless Steel Scourer with Plastic Handle). Extracellular and surface-Flexional Soft Head Electronic Digital Thermometer(Hydrogen Cylinders for Gas Filling Stations/Plants,Luxury Goose Duck Down Feather Filling Pillow for Hotel Home). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (China Top Supplier 2- (4-Chlorophenoxy) -2-Methylpropionic Acid with Best Price CAS: 882-09-7 C10h11clo3), which can be one important cause of the increase in coagulant demand in algae-rich waters (Durable Rectangular FRP Pultruded Grating for Glassfiber Platform).Wholesale 925 Sterling Silver Turkish Micro Pave Big Turquoise Evil Eye Pendant(2000W Stainless Steel CNC Fiber Metal Laser Cutting Machine), particularly humic susbtances. Humic substances are highly negatively charged (Double Wire Weave Stainless Steel Decorative Wire Mesh Panels), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Pgz1000 Crystal Industry Pneumatic Scraper Bottom Discharge Flat Basket Filter Centrifugal Separator). Maximal UV254removal was observed to be found around pH 6.0 (Eco-Friendly Euro Plastic Container with Lid). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Sri Lanka Metal Detector Handheld Metal Detector Explosive Detector).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Top Quality Polar Wohlenberg Paper Cutting Blade.
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